Method for selective extraction of surfactants from crude oil

Patent metadata

Field	Value
Publication number	US-2018291286-A1
Application number	US-201815935471-A
Country	US
Kind code	A1
Filing date	Mar 26, 2018
Priority date	Apr 5, 2017
Publication date	Oct 11, 2018
Grant date	—

Abstract

Processes for selective extraction of surface active naphthenic acids from high total acid number crude oils for use in enhanced oil recovery are provided.

First claim

1 . A method for selective extraction of surface active naphthenic acids from an acidic crude oil, comprising:
providing a crude oil having a total acid number (TAN) greater than 0.4; mixing the crude oil with an aqueous solution to extract a portion of naphthenic acids from the crude oil into the aqueous solution thereby creating a crude oil/water emulsion; wherein the aqueous solution comprises water and a weak base; separating the aqueous solution containing the portion of naphthenic acids from the crude oil; wherein the aqueous solution will contain an additional portion of the crude oil; adding a salt to the aqueous solution, thereby causing the additional portion of the crude oil to separate from the aqueous solution; removing the additional portion of the crude oil from the aqueous solution; and extracting the naphthenic acids from the aqueous solution.

2 . The method of claim 1 , wherein the pH of the aqueous solution is from 10.5 to 11.5.

3 . The method of claim 2 , wherein the pH of the aqueous solution is from 10.9 to 11.2.

4 . The method of claim 1 , wherein the adding the salt to the aqueous solution occurs prior to separating the aqueous solution containing the portion of naphthenic acids from the crude oil.

5 . The method of claim 1 , wherein the water is saltwater, wherein the adding a salt act is performed by virtue of the water being saltwater.

6 . The method of claim 1 , wherein the weak base is sodium carbonate.

7 . The method of claim 1 , wherein the extracting is performed via liquid-liquid extraction.

8 . The method of claim 1 , wherein the extracting is performed via solid-phase extraction.

9 . The method of claim 1 , wherein the salt is sodium chloride.

10 . The method of claim 1 , wherein the portion of naphthenic acids extracted from the crude oil are those naphthenic acids which are soluble in solutions with a pH less than 11.1.

11 . The method of claim 1 , wherein the portion of naphthenic acids extracted from the crude oil are those naphthenic acids having a molecular weight from 200 to 700.

12 . The method of claim 1 , wherein the mixing of the crude oil with an aqueous alkaline solution is carried out in a co-current or countercurrent flow or a mixing vessel.

13 . The method of claim 1 , wherein the extraction of the portion of naphthenic acids from the aqueous solution is carried out through a multistage liquid-liquid extraction using an organic solvent.

14 . The method of claim 13 , wherein the organic solvent is a dichloromethane solvent.

15 . A method for enhanced oil recovery, comprising:
selectively extracting surface active naphthenic acids from an acidic crude oil by the method of claim 1 ; injecting an aqueous alkaline solution at a pH of less than 11.1 containing the portion of naphthenic acids into a subterranean oil reservoir; recovering oil displaced by the aqueous solution.

16 . The method of claim 15 , wherein the aqueous solution containing the portion of naphthenic acids injected into the subterranean oil reservoir is saline, and is derived from seawater or produced water.

17 . The method of claim 15 , wherein the interfacial tension between aqueous solution containing the portion of naphthenic acids and the oil in the subterranean oil reservoir is reduced to less than 1 mN/m.

18 . The method of claim 15 , wherein the interfacial tension between aqueous solution containing the portion of naphthenic acids and the oil in the subterranean oil reservoir is reduced to less than 0.5 mN/m.

19 . The method of claim 15 , wherein the subterranean oil reservoir holds a crude with a total acid number less than 0.4.

20 . A method for enhanced oil recovery, comprising:
selectively extracting surface active naphthenic acids from an acidic crude oil by providing a crude oil having a total acid number (TAN) greater than 0.4; contacting the crude oil with a weak anion exchange (WAX) column to recover a portion of naphthenic acids from the crude; and washing the WAX column with a solution comprising a polar solvent and an acid to recover the portion of naphthenic acids; injecting an aqueous alkaline solution at a pH of less than 11.1 containing the portion of naphthenic acids into a subterranean oil reservoir; recovering oil displaced by the aqueous solution.

21 . The method of claim 20 , wherein the aqueous solution containing the portion of naphthenic acids injected into the subterranean oil reservoir is saline, and is derived from seawater or produced water

22 . The method of claim 20 , wherein the interfacial tension between aqueous solution containing the portion of naphthenic acids and the oil in the subterranean oil reservoir is reduced to less than 1 mN/m.

23 . The method of claim 20 , wherein the interfacial tension between aqueous solution containing the portion of naphthenic acids and the oil in the subterranean oil reservoir is reduced to less than 0.5 mN/m.

24 . The method of claim 20 , wherein the subterranean oil reservoir holds a crude with a total acid number less than 0.4.

25 . The method of claim 20 , wherein the polar solvent is a high polarity solvent, such as methanol.

26 . The method of claim 20 , wherein the polar solvent is a low polarity solvent, such as dichloromethane.

27 . The method of claim 20 , wherein the washing the WAX column is performed via a series of washes starting with a solution comprising a high polarity solvent and performing successive washes with solutions comprising decreasing polarity solvents.

Assignees

• Exxonmobil Res & Eng Co

Inventors

• Mohan Aruna
• Yeganeh Mohsen S
• Cherney Daniel P
• Mennito Anthony S
• Deighton Shane P
• Vreeland Jessica L

Classifications

• C10G2300/203

  Naphthenic acids, TAN · CPC title

• C10G53/12 Primary

  including at least one alkaline treatment step · CPC title

• C09K8/584

  characterised by the use of specific surfactants · CPC title

• E21B43/20

  Displacing by water · CPC title